The following clarification was printed in the Observer's For the record column, Sunday April 3 2005

In the article below we state that 'The use of ear [auricular] acupuncture in treating acute drug withdrawal began in Hong Kong in 1972.' We should clarify that in 1972 surgeons at Tung Wah Hospital discovered that electro-acupuncture could alleviate opiate withdrawal symptoms. It was some years later that surgeons at New York's Lincoln Hospital developed an acupuncture technique for addiction.

You have a crack cocaine habit that costs you £1,500 a day, forcing you into prostitution. Someone tells you about a course that could you get off the drug, without putting you on substitute medication, but it costs £15,000. What would you do - especially if you found out the course was linked to the Church of Scientology, the controversial creed that boasts John Travolta and Tom Cruise as followers?

For Danielle Medford, 22, there was no debate. Ravaged by crack, her body was close to shutdown. Death was only weeks away. Her family read about Narconon on the internet and raised the cash to enrol her as one of the drug rehabilitation programme's first British clients.

Danielle weighed just over seven stone when, she walked through the doors of the 1920s mansion in a quiet street in the Sussex town of St Leon ards on Sea. Seven weeks later, she weighs 10 stone, she is off crack and about to go to Barbados on holiday. When she returns, Danielle wants to work with schoolchildren to warn them of the dangers of drugs.

'The course teaches you that you can be anything you want to be,' Danielle says with a wide smile. 'I hit the jackpot with Narconon. I have a brand-new life. I have a little girl and I neglected her, but not any more.'

It was only later, as she was finishing her course, that Danielle became aware of Narconon's controversial rep utation. Its programme, which claims to have helped 'purify' 300,000 people around the world, has been attacked by mainstream drug experts alarmed at the way Narconon dispenses massive amounts of vitamins to its clients above recommended daily limits. They point out that Narconon's claims that it has a success rate of 80 per cent, are almost impossible to verify independently, and express concern that the programme is a recruiting ground for Scientology.

But it is clear that many people fervently believe in the programme - which they can quit at any time - and, like Danielle, have become evangelists for it. Cheers star Kirstie Alley is now a spokeswoman for the organisation, which she credits with helping her ditch her coke habit. American cult musician Beck played a Narconon fundraiser in Los Angeles last year. He told an interviewer last week: 'The drug-rehabilitation programmes have the highest success rate of any in the world.'

When the St Leonards' centre held an official opening three weeks ago, the former manager of the Rolling Stones, Andrew 'Loog' Oldham, a man who did more to boost the coffers of Colombia's drug barons than practically anyone else in the world with his unfettered cocaine consumption, flew in to praise Narconon and to thank it for saving his life.

'I had a rollercoaster of a ride with the Rolling Stones for five years and then spent 30 years getting over it,' he said. 'The programme was an amazing experience for me personally and also because of the people I met on it. It was a glorious seven weeks as the acid came out first, followed by the coke, morphine derivatives, inoculation poisions as well as_ all of the drugs of life.'

Impressed by such testimony, schools have started inviting Narconon, a registered charity in the UK, into their classrooms to warn pupils about drugs. Students are given pamphlets with information about the programme and a number to ring if they are worried that someone is using drugs.

Local government is also hoping to pay for treatment programmes at the 60-bed clinic. When The Observer became the first newspaper to be given access to the clinic last week, two social services workers were being given a tour of the building, once an asylum detention centre.

Already the centre's claims are having an impact on other drug rehabilitation centres. Several clients interviewed by The Observer said they had opted for Narconon over The Priory or Clouds - two of Britain's most famous rehab centres, whose claims at successfully treating addictions are far more modest than the new entrant.

Perhaps Narconon's claims explain why it charges so much. The average course lasts three months and costs £15,000. But its clients believe it is a small price to pay.

Ryan Jarvis, 27, developed such a cocaine and alcohol habit that he could not hold down his carpentry job. As his life collapsed around him, Ryan left his partner and their child and fled to Marbella. He blew £18,000 on a seven-month orgy of drink and drugs before his father lent him the cash for the Narconon course.

Ryan, whose worn face belies his age, says: '£15,000 is not a lot of money. Since I finished the course eight weeks ago I haven't got any problems. I'm back with my family and I have my life back.'

He admits he found parts of the course 'weird'. 'There was some stuff that wasn't my cup of tea, but a lot of it really helped me. You get out of the course what you put in.'

To the outsider, the entire programme must seem weird. Founded in 1966 by William Benitez, an inmate of Arizona State Prison, Narconon draws heavily on the teachings of L. Ron Hubbard, a science fiction writer and the founder of Scientology.

Critics argue Narconon is merely a front for Scientology. Hubbard's teachings and photos adorn the centre's walls and the language the staff use is redolent of Scientologists. Paul Dolan, the clinic's manager, admits he is a Scientologist and confirms that the centre could not have opened if it had not been for the generosity of members of the church. However, he denied suggestions that the clinic's profits will be ploughed into Scientology and insisted they will be invested in rolling the programme out nationwide, starting with London, Manchester and Glasgow centres.

Nevertheless, the overlap between the church and the drug rehabilitation programme alarms Scientology's critics. They point out that each Narconon client must complete eight books based on Hubbard's teachings during their course, which is in three parts - withdrawal, detoxification and education - and draws on the Scientology founder's beliefs about mental and physical health.

During the withdrawal phase, which typically lasts five to eight days, a client is put on a course of vitamins, including huge doses of Niacin and B3, and given 'assists' by staff - Scientology techniques similar to massages which apparently soothe mental and physical pain. 'Pretty much every other drug rehabilitation course prescribes drugs. We don't,' says Dolan, a former engineer in the gas industry.

Critics say there is no scientific basis for Narconon's programme and are alarmed at the amounts of vitamins it prescribes. Dolan dismisses the worries. 'You could give the people in here up to 1,000 times the recommended daily dose and it still wouldn't be a health threat, because the drugs they have been on strip the vitamins out of the body.'

Claire Smith (not her real name), who says she was admitted to the centre five weeks ago addicted to morphine, heroin and crack, claims to be living proof that addicts don't need medication to help with their withdrawal. 'I was so ill my body couldn't take the vitamins at first,' she said. 'I'd been on methadone before, but that didn't work, my whole body just ached. But when I came out of the sauna I felt great.'

The sauna holds almost mystical properties to those who have completed the Narconon course. Clients spend about five hours a day 'sweating out their toxins' for up to three weeks. Jimmy Mulligan, 48, said he had been an alcoholic for three decades. 'But when you come out of the sauna for the last time you are free of everything.' Now sober, Jimmy's only regret is that his time on the course is ending. 'I'm not just saying that, I really mean it.'

Upon arrival at a Narconon programme, all clients are issued with a Hubbard pamphlet, The Way to Happiness, A Common Sense Guide to Better Living . 'It is in your power to point the way to a less dangerous and happier life,' is the opening maxim. 'Be temperate' is another. 'Sex is a big step on the way to happiness and joy. There is nothing wrong with it, if it is followed with faithfulness and decency,' another says.

The perfunctory writings are typical of Narconon manuals. Yet Narconon believes that Hubbard's words hold the key to whether their clients stay off drugs or drink when they finish the course. Clients are encouraged to read dictionaries, not only to make sure they grasp every word of the teachings, but also to give them a feeling of empowerment. 'I learnt 400 words on my course, words like cognition,' Danielle says with pride. 'I've learnt more here than I learnt in school.'

Armed with their new education, which also involves working through problems with clay models and talking to an ethics counsellor to help develop a moral code, a Narconon client is deemed ready to face the world without risk of falling back into addiction.

Many, however, do not seem to want to go very far. Of the 15 people who have completed the Narconon course since the St Leonards' clinic opened, five are now working for the company. Jimmy intends to sign up as an employee when he finishes the programme.

Lucy Graham, 22, who says she was on the verge of suicide because of binge drinking and bulimia, went home to Swindon after the course. 'But I really wanted to come back. It's made such a difference to my life. I'm now training to be a public relations manager for Narconon.'

Narconon, it seems, may set its clients free, but they don't want to be free of Narconon. As Hubbard writes: 'The way to happiness is a high-speed road to those who know where the edges are.'

To its believers, Narconon knows exactly where those edges are.

How to beat an addiction

The 12 steps

Chiefly used by recovering alcoholics, 12 Steps encourages addicts to admit they are powerless without alcohol and that their lives have become unmanageable. Through a mixture of prayer and meditation, addicts improve their contact with God to gain the strength to break free of their addiction.

The Thamkrabok monastery

The Thailand drug rehabilitation centre offers the toughest recovery regime in the world. The rock star Pete Doherty visited the monastery in an attempt to rid himself of his crack cocaine habit, but didn't last the course. Addicts are put through a series of bamboo floggings, prayers and manual labour which is designed to cleanse them physically and mentally.

The Priory

The UK's most famous rehab centre offers a range of therapies for addicts, most of whom will have to pay for its services. A personalised addiction treatment programme will cost around £25,000.

Acupuncture

The use of auricular (ear) acupuncture in treating acute drug withdrawal began in Hong Kong in 1972. Its practical application in alcohol and drug treatment evolved at New York City's Lincoln Hospital during the Seventies and is now used by 2,000 clinics worldwide.